One conventional carton handling system for loading lettuce cartons into the cargo space of a transport vehicle at a loading dock is described in U.S. Pat. No. 4,439,093. In this complex system, the pallets are removed from the stack of cartons by a depalletizing machine and the stack is then deposited onto a forklift truck that is equipped with a pusher attachment. The forklift truck then carries the stack of cartons into the cargo space of the transport vehicle whereafter the cartons are pushed-off the tines of the lift truck and onto the floor of the vehicle.
The next following stack of cartons is placed on the top of the first stack to utilize the available height of the cargo space. This loading procedure is repeated until the cargo space is at least substantially filled with cartons. This type of system gives rise to carton damage, spillage and related problems well-known to those skilled in the art.
Further, the depalletizing machine must be closely monitored by a separate workman and the loading cycle is prone to delays, primarily due to occasional pallet jam-ups and resultant damage to the pallets and cartons. Still further, a substantially large dock loading area is required to accommodate the bulky and complex depalletizing machine whereby the number of companies enabled to use this type of system is severely limited. The depalletizing machine also requires constant servicing and specially designed high voltage electrical hook ups. In addition, seasonal moves of the depalletizing machine to various locations requires its disassembly, shipment and reassembly, thus giving rise to unduly high labor and related costs.
Even more importantly, this conventional system does not facilitate mechanized removal of the cartons from the transport vehicle by the end user or buyer. In particular, the cartons must be removed manually from the transport vehicle by workmen who must then stack the individual cartons onto a standard pallet for transfer to delivery transport vehicles. In addition to giving rise to excessive labor costs, delayed unloading ensues which has proven costly and inconvenient to the end user.
A second conventional "rack loading" system involves the use of a loading rack that has a width slightly less than the average width of the cargo space of a standard transport vehicle. The cartons are stacked six layers high on the rack with two more layers of cartons being placed thereon to maximize use of the cargo space. The tines of a lift truck are then used to place the loaded rack into the cargo space with the process being repeated until the cargo space is loaded to order.
The latter system also gives rise to carton damage and related problems. Since the width of the rack is necessarily less than the width of the cargo space of a standard transport vehicle, the cartons tend to break over the ends of the racks, resulting in carton damage or breakdown. Squeezing of the cartons by the clamps of a lift truck also subjects the cartons to damage. Most importantly, this system also does not provide for the mechanical unloading of the cartons, but rather requires manual labor to do so.
A third conventional loading system, which has proven quite successful, is disclosed in U.S. Pat. No. 4,640,657. Although successful, such system also is not conducive to the mechanical unloading of cartons from a transport vehicle and requires specially designed equipment as described in this patent.